


Supergirl-in-Training

by beerbad



Category: Supergirl (TV 2015)
Genre: Cuddling & Snuggling, Dom/sub, F/F, Fluff, Master/Pet, Mommy Kink, Non-Sexual Age Play, Non-Sexual Submission, Older Woman/Younger Woman, Pet Names, Sister-Sister Relationship, Workplace Relationship
Language: English
Status: Completed
Published: 2015-11-29
Updated: 2016-01-30
Packaged: 2018-05-03 22:21:44
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 4,453
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5309201
Author URL: https://archiveofourown.org/users/beerbad/pseuds/beerbad
Summary: <blockquote class="userstuff">
              <p>“You’re so in control and in charge with all this Supergirl stuff all the time, plus dealing with your job and personal life… I think it would be really good for you to give someone else the control for a little while.”</p><p>In which Alex and Cat conspire to help Kara cope with her responsibilities.</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> Written because I couldn't last another day without reading sub!Kara. :3

It’s Friday morning. Friday. Kara smiles to herself as a little pang of nervous excitement shoots through her chest. It’s a strange feeling, like fear and happiness at the same time. It’s what she expects someone would feel when they’re on a date with someone they really like, or in this case, apparently the feeling one gets when one’s boss and one’s sister have conspired against them.

Kara walks into the ground floor of the CatCo building, the thumping in her chest building as she takes the elevator to the office. She grips Ms. Grant’s latte and strudel in hand, feeling the anticipation as the elevator dings. Just like any other day in the office… except it isn’t. Fridays are different.

Kara stops briefly at her desk to say hi to Winn, but cuts him off as soon as he starts trying to turn it into a real conversation. She can’t be late. “You know how she is!” is Kara’s apology as she makes a beeline to Ms. Grant’s office.

“Good morning, Ms. Grant! I brought you your--”

The icy stare she’s met with is enough to make Kara forfeit the end of her sentence. _Latte. And strudel that I’m sure is trashcan-bound._

“Shush. I can’t deal with your endlessly chipper attitude this early in the morning. Frankly I don’t know how your sister does it.” She takes the cup and bag from Kara’s hands. “And lucky for me, today is the one day of the week when I don’t have to deal with it at all. Now sit.”

“Yes, Ms. Grant.” Kara looks around. On the couch, probably? Or… “Um, where, Ms. Grant?” Kara wishes the demand had been more specific. She doesn’t want to make a mistake this early in the day.

“Oh, so that’s how it’s going to be today, is it? Little Kara needing every tiny thing spelled out for her. _Right. Here._ ” She gestures with the toe of her stiletto to the floor space beside her, and Kara _almost_ asks if she should bring a chair but doesn’t want to push her luck. Kara nods instead and settles herself down, kneeling, next to Ms. Grant’s chair behind the desk.

“Now I’m sure you have lots of important work to do today at your desk. If you’re a very good girl I might even let you do some of it. But that’s not looking too likely, is it?”

Kara glances up at her boss with her patented puppy-dog look, all long eyelashes and round eyes. This look _always_ worked on Eliza, to Alex’s continual dismay. “I want to be good, Ms. Grant.” Kara really means it, too. She always means it.

Letting out a sigh, Ms. Grant drops the bag of strudel at her feet. “Even Supergirl can’t be good _all_ the time. Eat up, kitten.”

Kara devours the strudel, leaving her hands sticky and cherry filling on her cheeks. She squirms a little, not knowing what to do with herself.

It takes her boss a solid fifteen minutes before looking down at her again. After taking in the sight of her pet, Ms. Grant grabs a tissue and bends down with a slight look of disgust on her face. “You really are a child. That’s what I get for hiring twenty-somethings,” Ms. Grant remarks as she wipes the remains of strudel off of Kara’s hands and face.

Another thirty minutes pass of Kara on her knees in silence before she just has to say _something_. Her boss has been staring at the same page of layouts for what feels like forever, and shouldn’t she be a helpful employee?

“Ms. Grant, can I help you with those?” Kara questions as she looks up.

“Darling, the only thing you can help me with today is following my instructions and doing exactly as I say. Do I make myself clear?” Kara nods. “Right now I merely want you where I can see you, so that I can make sure you’re not wasting your workday chatting with those imbecile male coworkers of yours.”

Eventually Kara dares to switch positions, as super strong joints unfortunately do not seem to be part of her package. As if suddenly remembering her presence, Ms. Grant takes one hand away from the layouts to pet Kara’s hair. Kara is grateful that she’s behind the desk at times like this, though part of her can’t help but wonder how the other CatCo employees would react to their boss casually petting her assistant. They’d probably be too scared to stare or question it, she thinks. It’s a relief, considering the office is basically a fishbowl with its glass walls.

Finally Ms. Grant sends her to get lunch, and Kara is grateful to stretch her legs. “You have exactly ten minutes to get back here, and believe me, I will be counting,” Ms. Grant says without looking up from her work.

When Kara makes it back with 28 seconds to spare, she swears her boss almost looks pleased. “Good girl,” Ms. Grant says in affirmation, “at least you’re not completely useless.” _Ah. There it is._

Ms. Grant sits down on one of the couches in her office to eat her lunch, and pats the space next to her without making eye contact with Kara. At least it’s the couch this time. Ms. Grant has some of the layouts with her to study while she eats, ever the multitasker. She finally, _finally_ asks Kara for her opinion, and just as Kara is suggesting that they re-title one of the articles Ms. Grant starts to tear off little pieces of her sandwich and hand them to her.

Kara doesn’t know how to react other than to eat the offerings. She wouldn’t want to be impolite, after all, and she also has a sneaking feeling that this might be all the lunch she gets. But then she remembers that Alex will make her dinner tonight, because that’s the Friday arrangement, and in the meantime Ms. Grant is actually feeding her and giving her attention and not yelling. A warmth spreads through Kara’s chest as she offers up another suggestion about reordering a couple of the articles in the issue they’re working on.

After she’s done eating, Ms. Grant pats her lap and Kara’s eyes go wide -- does she want Kara to actually sit on her lap?? With an exasperated sigh, Ms. Grant clarifies, “Lie down, kitten. Mommy still has work to do.”

Well this is new. Kara carefully, gently slides her body onto the couch and rests her head in Ms. Grant’s lap. Her _boss’s_ lap. After a minute or two of trepidation, Kara feels herself start to relax. While Ms. Grant flips through CatCo social media posts on her tablet, Kara closes her eyes and thinks back to a few weeks ago when this all started.

~~~

“My _boss_ , Alex. You talked to my boss?!” Kara exclaimed, pacing around her apartment.

“She actually contacted me. It turns out we both have the same concerns about you, you know."

How did Ms. Grant even _get_ Alex’s email address? Then she heard her boss’s voice in her head: _“I run one of the top media companies in the country, Kara. And you don’t think I can manage to track down my assistant’s sister’s email address?”_

“We think you’ve taken on too much, too soon. Frankly, Cat believes you’d do a better job in the office if you weren’t so constantly frazzled, and you know I’m just worried about you. So that’s how we came up with this plan,” Alex explained in a calming tone.

“So let me get this straight. Once a week I will be Ms. Grant’s slave -- which I already am, by the way -- and then I’ll come back here and be your… what? Your little sister? I’m already that, too!”

“Her _pet_ , Kara. And yes, you’ll still be my little sister, you’d just get to be littler than usual. Think about it. You’re so in control and in charge with all this Supergirl stuff all the time, plus dealing with your job and personal life… I think it would be really good for you to give someone else the control for a little while.”

Kara took a deep breath. “Okay. But if I want to stop we can stop, right? Ms. Grant will stop?”

Alex walked over to her and put a reassuring hand on Kara’s arm. “Of _course_. Cat definitely doesn’t need a sexual harassment lawsuit to deal with on top of everything.”

It alarmed Kara only a little bit that her sister and Ms. Grant were apparently on a first-name basis now.

~~~

Kara’s focus comes back to the present when she feels Ms. Grant start to run long fingers through Kara’s hair, stroking her as if she were a kitten in Ms. Grant’s lap. _No pun intended._ Kara does appreciate the metaphor though, and is tempted to start purring because it feels so nice. That would really complete the picture.

**Notes for the Chapter:**

> I have at least 3 chapters planned out, but there could possibly be more, and I'll add tags as I go! Don't want to spoil too much. ;) I'm also still deciding if I'm going to keep it nonsexual or not. I'd love to hear any ideas/thoughts/feedback you might have. :)


	2. Chapter 2

Kara’s almost asleep, head still cradled in Ms. Grant’s lap, drifting to the oddly soothing background noise of her boss yelling at Financial over the phone. She wonders when Ms. Grant’s disapproval shifted from something that only scared her to something that's now almost a security blanket.

Kara feels like she could stay like this forever, but she really needs to pee, and she already learned the hard way that Ms. Grant’s pet is not allowed to simply walk to the restroom when the need arises. The first time she’d tried it resulted in her boss accompanying her into the bathroom and delivering several sharp slaps to her bottom before she was allowed to proceed, all under Ms. Grant’s watchful eye. Ms. Grant had even helped her wash her hands afterwards, insisting due to Kara’s “obvious incompetence”.

She can’t imagine what would become of her if she dared interrupt Ms. Grant’s phone call to ask permission, so Kara settles on squirming around to try and find a position that will relieve some of the pressure on her bladder.

Finally the phone call ends, but Ms. Grant doesn’t seem to notice Kara’s discomfort _(or just doesn’t care)_. Kara knows she should just tell her, but it’s so embarrassing. Her cheeks flush at the thought, so she wriggles around a bit more instead.

Ms. Grant moves her hand from Kara’s hair to put firm pressure on her back. “ _Stop. Moving._ I simply can’t concentrate with you wiggling around like that. You’re here to help me stay focused, not roll around on my couch like an overexcited puppy.”

“Yes, Ms. Grant,” Kara attempts to get out, but she has to go really bad now and can’t resist another shift in position. She’s immediately reprimanded by a slap on her butt, the sudden surprise contact causing a little pee to leak into her underwear. If she doesn’t say anything now this is gonna get a lot worse.

“Ineedtopeereallybad!!” she admits, and Ms. Grant raises an eyebrow.

“Try again, kitten. Manners, now. This is a civilized workplace.”

“Ms. Grant may I please go to the bathroom _please_ ,” Kara tries. She’s sure her boss doesn’t want to deal with a mess on her expensive furniture. Or so Kara hopes.

“Yes, I suppose you may,” Ms. Grant answers at last, and Kara jumps to her feet. “On your knees, darling,” she adds.

Kara’s in too much of a hurry to protest, so she gets on all fours and makes her way as fast as she can to the private executive restroom adjoined to Ms. Grant’s office. At least she doesn’t have to go very far.

~~~

Before Kara knows it the workday’s over, Ms. Grant looking her straight in the eye as Kara gets to her feet. “You can do better. You’re _very_ good, kitten, but I expect the best.” Ms. Grant strokes her hair and cups her cheek one last time in parting, and Kara almost doesn’t want to leave.

But Alex is waiting for her in the lobby, and Kara’s heart does that nervous-excited thing all over again as she steps out of the elevator. She resists the urge to run over to her sister and tackle her with a hug (there’s plenty of time for that at home), but Alex’s warm smile feels like a magnetic pull.

Alex envelops Kara in her arms, kissing her on the cheek. “How was your day, sweetheart? Were you a good girl for Ms. Grant?”

When Kara doesn’t immediately answer, Alex pulls back to look at her. “I think so…” Kara tries, but her damp underwear is a constant reminder that maybe there was some room for improvement.

“You know Cat will be giving me the whole play-by-play later, so you might as well tell me.”

“I tried really hard, Alex. I promise! You know how Ms. Grant is…”

Alex raises a skeptical eyebrow at her but thankfully drops her inquiry. “Okay,” Alex says as she takes Kara’s hand. “Let’s go home, little bear.”

In this case ‘home’ is Alex’s apartment, where Kara stays every Friday night. It’s much tidier than Kara’s, and she’s noticed that everything seems extra-pristine on Fridays in particular. Kara enjoys the thought of Alex preparing for her, getting into her own headspace as she cleans and organizes.

Kara clings to Alex’s hand for the duration of the journey home, feeling as if she could actually get lost in the busy city if she were to let go. Alex is her tether, her lifeline when she’s in this headspace, and it’s almost alarming how natural it feels. On these days, it’s like the connection between them has been turned up to 11.

They’ve barely set one foot into Alex’s apartment when Kara goes in for another hug, having no need to play it cool now that they’re alone. She presses her body as close to her sister’s as possible, taking Alex in with all her super-senses -- her smell, her warmth, the sound of her heartbeat. Kara buries her face in Alex’s neck, nuzzling into her.

Alex smiles and holds her close. “Someone’s happy to be home. Now let’s get you out of these work clothes.”

Alex takes Kara’s hand again and leads her to the bedroom, where Kara’s pajamas are laid out on the bed waiting for her. In a nice nod to Kara’s other identity, Alex has chosen a red and blue striped set made out of stretchy cotton. They sit on the bed as Alex helps Kara undress, undoing the buttons of her blouse, unclasping her bra, helping her step out of her skirt and tights. She can feel Alex’s affection for her through the movements of her sister's hands, gentle and competent and soothing.

Kara’s down to her underwear when she suddenly blushes, knowing that her earlier accident won’t escape someone as focused and detail-oriented as her sister. Indeed, Alex frowns as she removes the final article of clothing from Kara’s body, moving to place the panties in her hamper.

“Kara, did you have an accident at work?” Alex’s voice is stern now, though not unkind.

Kara flushes again, shifting on the bed. “Only a teeny little one! I just waited too long to tell Ms. Grant that I needed to go.”

Alex sits back down. “And did she punish you?”

“Not really… I mean she didn’t even know that I went a little.” Her sister seems to be contemplating this development, and Kara knows it’s time to break out the puppy-dog look again. “Are you… going to punish me?” Kara raises her eyebrows, giving her sister her best ‘I-couldn’t-help-it’ pout.

“No,” Alex finally answers, “but I am going to be speaking to Cat about this.” She reaches under the bed, and Kara knows what’s coming. “And I think you need a pull-up tonight.”

If this is her only consequence, Kara can’t really complain. Alex had delicately brought up the subject when the Friday arrangement began, claiming that wearing pull-ups might help Kara get into a littler headspace. After the first week, Kara had agreed to it -- they were easy to get in and out of, and she didn’t have to actually _use_ them. Kara knew that there were all sorts of Earth taboos about things like this, but frankly it didn’t seem like such a big deal to her. They felt nice and she knew Alex thought she looked cute, and that was all that mattered.

After Alex gets the pull-up on her, she helps Kara with her pajamas. “I need Buddy!” Kara exclaims, as if it should be obvious.

“What do you say?”

“Please,” she adds, and Alex leans over to grab the stuffed dog from his place on the pillows.

“Happy now?” Alex asks with mock annoyance in her voice.

“Mmm-hmm.” Kara hugs her dog and rubs his soft fur against her face. Getting cuddly toys is certainly one of the best parts of their arrangement, she thinks.

Alex kisses her cheek. “Good.”

**Notes for the Chapter:**

> Thank you so much to everyone who's been reading. :D


	3. Chapter 3

**Notes for the Chapter:**

> Thanks to everyone for your patience while Star Wars fic ate my brain. :T This chapter is an immediate continuation of the previous one.

Alex brushes Kara’s hair behind her ear and then gets off the bed, holding a hand out to her little sister. Kara looks up at her expectantly, and Alex feels that little pang in her heart -- her sister is so open and trusting, and it’s _Alex_ she’s looking to. Alex had always been tasked with protecting Kara, but it feels so different and special on nights like this. Since putting on the cape, Kara had needed her big sister less and less (Alex hates to admit to herself), but now here she is, vulnerable and submissive and ready for Alex to take the reins. And the thought that Kara would give herself like this to Alex willingly…. Alex had been pretty sure that this arrangement would help Kara, she just hadn’t anticipated how much she herself would get out of it.

“It’s time to make dinner, little bear. Are you hungry?” Kara nods as she takes Alex’s hand and allows herself to be led out of the bedroom, stuffed dog in tow under one arm. Alex wonders how much she had to eat at the office today, and makes a mental note to ask Cat in her email later. Thanks to her Kryptonian metabolism, though, Kara always seemed ready to eat.

“How long will it take? Can I help you cook? What’s for dessert?” Kara wonders. Alex rolls her eyes at her sister’s flurry of questions.

“Right now you and Buddy need to stay out of the kitchen and let me work. But I set up your coloring supplies on the coffee table; do you think you can keep yourself occupied for a little while?”

“Okay!” Kara replies, happily sitting herself down on the floor in the living room. Before they started their Friday ritual, Alex was curious as to what her sister would be like in a submissive headspace. In retrospect, she should’ve guessed that Kara would be even more cheerful than usual, if that was somehow possible.

Kara dives into her coloring right away, carefully selecting the perfect colors from her box of crayons as Buddy looks on from the sidelines. Alex gets to work on their meal, affection for her sister blooming in her chest as she observes the intense look of concentration on Kara’s face. It’s the same look she gets when she’s hunting down alien threats or proofreading an article for Cat late at night, only this time Kara’s in striped pajamas with the top of a pull-up peaking out of her waistband. Alex would find the scene hilarious if it wasn’t just so damn adorable.

Thirty minutes later, their food is ready. “It’s time for dinner, little bear,” Alex calls to Kara. “Come wash your hands.” When she doesn’t receive an answer, Alex walks over to the living room. Kara’s still enveloped in her coloring, and Alex can appreciate the bright, intricate patterns her artistically-inclined little sister is working on. But Alex can’t let the disobedience fly -- part of caring for little Kara includes giving up her usual lenience towards her sister.

“Kara,” Alex warns, her voice firm, “come on.”

“But I just want to finish--”

Alex swiftly cuts her off. “No, it’s dinner time now, you can draw more later.”

Kara pouts, a pitiful look on her face, but gets up and follows Alex into the kitchen. Alex helps Kara wash her hands in the sink, giving her sister’s shoulder a gentle squeeze. On these nights Alex can’t help but want to show Kara some extra affection, to touch her, to let her hands show Kara how much she is loved.

After they finish eating Alex grabs a damp cloth to scrub Kara down again. Her sister is an enthusiastic, messy eater even in her normal state, and seems to be even less coordinated when she’s little. Alex and Cat had had a good laugh over email about this subject, in fact. _I’ll send you pictures next time_ , Cat had written after an incident with several sticky buns. _She’s impossible. And adorable, but frankly I don’t know how she survives without us._

“Okay, you can finish your coloring now. Buddy’s starting to look a little lonely over there.” Alex nods toward the living room as she loads the dishwasher.

“Yeah, I think he is,” Kara agrees. “Ooh, Alex, let’s watch a movie! Can we watch a movie?!” Her sister looks at her expectantly as she sits back down at the coffee table.

“I don’t know, do you think you deserve a movie today? What would Cat say?” Kara looks sheepish at that. “How about a show instead?” Alex offers before Kara can start doing that impossibly cute thing with her eyebrows.

Kara perks up again at the compromise. “Do you still have that Homeland episode that I missed on your DVR?”

“Uh-uh, I don’t think so, young lady,” Alex says with a grin. “Not tonight. Homeland is a very mature show for very mature people.” Kara is about to protest when Alex gestures to the box of crayons on the table. Point made.

They settle on Adventure Time, and Kara continues her drawing while Alex’s mind wanders. She wonders if Cat has ever seen Adventure Time -- maybe with Carter? She tries to imagine Cat sitting next to them and almost laughs at the picture. Surely Cat would criticize Princess Bubblegum’s handling of her subordinates.

Eventually Kara seems restless, bouncing on her knees. When she continues to shift her position, Alex leans over from her seat on the couch to put a steadying hand on Kara’s back. “I think you need to go potty.”

“Maybe,” Kara admits, “but I don’t want to miss anything.”

Alex sighs. “The pause button exists, you know. Now go on, we don’t want a repeat of earlier today…”

Kara flushes visibly at that, but doesn’t move. “Do you need me to come with you?” Alex asks as a final warning.

“No, just Buddy.” Kara finally stands, grabbing her stuffed dog. Alex smiles to herself as her sister makes her way to the bathroom, and takes the opportunity to change into her own pajamas while the show’s paused.

When Kara gets back she climbs onto the couch, abandoning her beloved crayons at last. She lays her head in Alex’s lap, Buddy tucked securely under her arm. “I laid like this with Ms. Grant today,” Kara notes as Alex resumes the show.

“You did, did you?” Alex asks with some surprise. It was hard to picture Cat as the cuddling type -- especially semi-publicly in her office. “Was it nice?”

“Mmm-hmm. Really nice. Well, until she swatted me for being too squirmy.”

“Squirmy? _You?_ I can’t imagine,” Alex teases, moving her hands down to tickle Kara’s sides. Her sister shrieks with laughter, body convulsing as she tries to move away from Alex’s hands.

“Okay, okay,” Alex relents after a couple minutes. “I suppose I should be trying to calm you down, not rile you up.” Kara giggles, her head coming to rest once again on Alex’s thigh. “One more episode, and then it’s into bed for you.” Kara sighs audibly, but otherwise doesn’t protest.

Alex gently plays with Kara’s hair and rubs her back while they watch their final episode, and she feels her little sister start to sink into relaxation. Alex never expected that this would feel so fulfilling, knowing that she’s able to help Kara like this. She smiles to herself as she watches Kara’s steady breathing.

Kara’s still awake, although just barely, when the show ends, and Alex leans down to kiss her cheek before taking her hand and leading Kara to the bedroom.

“Story? _Please?_ ” Kara asks immediately, before Alex can even get her into bed. Alex shoots her an exasperated look, although she already knows she’s going to give in to the request.

“Okay, but only if you brush your teeth and try to use the bathroom again first,” Alex negotiates.

“You know my bladder isn’t actually the size of a small child’s, don’t you?” Kara counters.

Alex raises her eyebrows. “Don’t argue with me. If you want your story, Buddy and I will be right here waiting for you.”

Alex runs a hand through the dog’s soft fur while she waits for her sister, and opens her nightstand to pull out a paperback copy of _Matilda_.

Kara reappears, and Alex holds out a hand to her. “Come here, little bear,” she calls softly, and Kara climbs onto the bed and slips under the covers next to her. “Good girl.” This might be Alex’s favorite part of their Friday night ritual, she thinks. She hands over Buddy and opens the book to the next chapter. She’s had to limit their reading to one chapter each time, otherwise Kara would be up half the night trying to get her to keep going. And Alex never had the energy for that at this hour.

As Alex begins to read, Kara snuggles into her happily, resting her cheek against Alex’s chest and laying her arm against her sister’s stomach. Alex holds the book in one hand so she can play with Kara’s hair with the other, causing the girl to nuzzle into her as she makes little sounds of contentment. Kara can definitely be a fierce, strong-willed person, but when she’s like this she might as well be putty in Alex’s hands.

“Okay, sweetheart, it’s bedtime,” Alex says in a quiet voice when the chapter’s over. Kara grumbles but closes her eyes, not moving from her position against her sister. “Did you have a nice day?”

Kara nods and smiles against her. “Mmm-hmm. I love you, Alex.”

“Good.” Alex leans down to gently brush her sister’s lips with her own. “I love you too, little one. Sleep well.”

Another successful Friday, Alex thinks as she closes her eyes. She’ll send the play-by-play to Cat tomorrow morning.

**Notes for the Chapter:**

> A huge thank you to everyone who's commented and left kudos!! I do have more planned for this universe, so stay tuned for a new fic in this series. :) Next one will have more angst and hurt/comfort.


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